The flax is a highly nutritious plant. It could be advantageously utilized in human nourishment on account of its high protein and oil content. Compared to other nutritive material sources it is the flax that contains the greatest amount of unsaturated fatty acids including alpha-linolenic acid of type omega 3 which is essential for the human organism [see Table 1; Bene et al.: “Szappanok és mosószerek” (Soaps and detergents), Müuszaki Könyvkiadó, Budapest, 1957].
TABLE 1Average percentage distribution of the fatty acids of more important fatsSaturationSaturated acidUnsaturated acidNumber of carbon atoms12141618201818181822The name of fatty acidLauricMyristcPalmiticStearicArachicOthersOleicLinolicLinolenicRicinoleicErucidicOthersCoconaut oil63188362Palmnut oil571582171Mutton tallow525312361Beef tallow3282012442Pork fat128124865Bone fat2019556Palm oil4384468Olive oil102808Castor oil48286Groundnut oil7466221Rapeseed oil222618250Rice germ oil182147284Sesame oil1024939Cotton-seed oil122228452Soybean oil17526556Grape-seed oil623755Corn oil844642Pumpkin-seed oil1363744Tomato-seed oil1571662Sunflower oil423856Linseed oil1093744
The flax seed, as far as the composition of the contained nutritive materials is concerned, has excellent properties [see: USDA National Nutrient Database for Standard References, Release 17 (2004)]. Furthermore, it contains phyto-hormones (lignans) in great quantity which certifiably have anticancer effect (see e.g.: Carcinogenesis 20(9): 1831-1835, 1999; Nutr. Cancer 43(2): 187-192, 2002). On the basis of the properties of the contents it is desirable that the flax should be an integrated part of the nutrition and it should be utilised in the food industry in a wide range. For the time being the utilisation of the flaxseed, is however, for many reasons, very limited.
The reasons for this situation can be summarized as follows.                1. The oil content of flaxseed can reach 40-50% and the oils occurring in this oil content belong to the so-called drying oils. Because a considerable part are unsaturated their melting points are very low, and because they are unsaturated they react very quickly with the oxygen in the air and quickly become rancid. Because of the rancidity a so-called “varnish” taste develops which makes the flaxseed less suitable for human consumption. Though by milling of the flaxseed the active ingredients become accessible, the milled product, is however, difficult to store and the amount of essential fatty acids of type omega 3 decreases already during the milling.        2. Another property greatly limiting the application of flaxseed is that it contains in the outer surface of the seed husk a very complicated, pectin-like material with a composition unknown up to now. The role of this material is to protect the seeds passing through the digestive tract of an animal that they may remain viable. Similarly, the human digestive tract is also unable to digest the raw, untreated seed, 1 kg flaxseed is able to bind 5 litres of water in consequence of which the gastric juice is not able to reach the surface of seed husk, and this slippery, gel-like material significantly enhances the intestinal activity, and functions as a purgative substance in countless cases. The internal content of the seed cannot, however, be utilized.        3. Furthermore, it is known that the mucilage of the flaxseed contains a lot of materials hindering the digestion, e.g. hydrocyanids and trypsine inhibitors. Though their effect can be decreased by heat treatment, their hindering effect cannot be completely eliminated (Journal of the American Oil Chemists' Society 70(9): 899-904, 1993). For this reason the removal of mucilage should be very desirable to ensure better digestion and absorption.        
Of course, lots of attempts have been made to eliminate the above mentioned problems. One such programme is mixing flax seed into the fodder of domestic animals, and by subsequently consuming and digesting the meat of animals bred on flax seed a person will be able to absorb the essential fatty acids. The effectiveness of this method, however, is very low, and what is more, the meat of the animals can have a “varnish” taste as a consequence of the rancidity. In another attempt, flax seed is mixed to the bakery products. In this case the mucilaginous materials are not damaged during the bake and the seeds remain undigested, their advantageous effect to the intestines remains only as fibres.
We have to mention that there have been a lot of attempts in connection with the removal of mucilage from the surface of flaxseed. Kalac J. and Rexova L. (Biochim. Biophys. Acta 167(3): 590-596, 1968) applied the mucilage as a test material to characterize an enzyme isolated from Aspergillus niger; during this experiment they worked with a mucilage available in trade. Though the aim of their experiments was absolutely different from the aim of the present invention, their results showed that the pectin-like mucilage of flaxseed can be partially disintegrated. Wanasundara P. and Shahidi F. (Food Chemistry 59(1): 47-55, 1997) used an enzymatic process in order to promote the protein digestion of flax meal obtained through milling of the flax seed. In this process the flax seed mucilage was only partially removed and the possibility of sprouting was excluded.
Another remarkable attempt relates to the feeding of broiler chickens (Br. Poult. Sci. 44(1): 67-74, 2003). Alzueta R. et al. reported that the inclusion of whole flax seed (with the mucilage) milled together in the chicken feed resulted in a mass reduction instead of mass growth in spite of the fact, that the nutritive value of the flaxseed is very high. Including milled flaxseed with reduced mucilage content to the feed, however, improved the utilization. It should also be noted that in this case only a partial removal of mucilage (about 83%) is reached so the results do not reflect a complete utilization. Moreover, the acidic removal of the mucilage and the high temperature applied (80° C.). cause the seeds to loose viability and cannot germinate.
From the point of view of the preservation of active ingredients the most successful procedure is the sprouting of the flax seeds. It is known that the oil present in large quantities in the living seedlings does not become rancid, and the valuable active ingredients are presumably protected against external oxidation processes as they are enclosed into micelles. At present the sprouting of flax seeds, however, has considerable limits. The gel-like material surrounding the husk (so-called mucilage) prevents direct sprouting and the external sterilization of seeds, which is the precautionary measure necessary for distribution. This is why it is necessary to use roundabout solutions. The seeds can, for example, be sprouted on some kind of carrier material (soil layer, cotton fabric, diaper material, etc.), and the green parts of plants can be consumed only by harvesting the cotyledonous plants. This application, however, is very elaborate, and its application is not suited for large scale production. Another disadvantage is the fact that when the cotyledons become green, already significant energy has been drawn from the seed, the development of bitter tastes starts, and the decomposition of multiple unsaturated fatty acids begins, resulting in a limited storability of the plant material (10-12 days).
In the patent publication document No. WO 03/003854 Barker D. et al. introduced a sprouting process in order to increase the relative amount of alpha-linolenic acid in the sprout product. In addition to the fact that we were not able to repeat these results, the aim of the procedure reviewed in the mentioned patent publication document No. WO 03/003854 was not the removal of mucilage hindering the digestion, and does not solve that problem at all. Though the composition of the sprout material was improved with this introduced method, it is very likely that the absorption of these compounds does not happen in the animal and human organism. Furthermore, the method elaborated by Barker D. et al. does not allow for the surface sterilization according to the requirements of food-hygiene.
The flax seed mucilage is by itself an interesting and valuable material. A lot of articles dealt with its investigation (see e.g.: Journal of Food Science 54(5): 1302-1305, 1989; Food Hydrocolloids 17(2): 221, 2003; Chromatographia 58(5-6): 331-335, 2003). The flax seed mucilage is indigestible for the human organism, therefore this material is called water-soluble fibre material (Philips G. O., Food Hydrocolloids 17(2): 221, 2003). According to experiences this material forms a thin layer on the stomach wall and the villi; this layer has both a strong laxative effect, and also prevents the absorption of nutritive substances. Thus it can be utilized as an additive for slimming agents.
The aim of present invention is to eliminate the above-mentioned problems and to bring the flaxseed into a suitable form for direct human consumption. We have found that this aim can be reached by removing the mucilage from the surface of flax seed. Through this process the flax seeds are deprived of mucilage, and then the seeds are germinated. The sprouted flax seed become accessible for the gastric juices, and the hard to digest oils are mobilized in the sprouting flaxseed. The flax sprout thus becomes suitable for direct human consumption or can be utilized as a basic food material. A further aim was to preserve the vitability of the seeds in order to retain their ability to sprout and also to gain access to their inherent values.
Thus, the objective of the present invention has been to work out a process suitable for completely removing the gel-like mucilage from the surface of the flax seed and thereby to make the surface of flax seed suitable for direct sterilization and sprouting.
The composition of mucilage surrounding the flaxseed is only partially known, this problem is not completely solved yet. Anyway, a complex molecule with a very complicated composition is in question, the removal and decomposition of which presents a problem so far unresolved. The results till now show only the fact that there is an enzyme which begins the partial decomposition of mucilage. During our experiments it was proved that in the case of different cultivated flax varieties the composition of mucilage can vary considerably from variety to variety as they react to the enzymatic treatment in a very different ways.
The mucilaginous material from the flax seed steeped in water could not be removed by washing, pressing and intensive agitation. The expression “removal” means an almost 100% removal, as the seeds can be sterilized only in this way. On the basis of this fact it is presumed that the mucilaginous material has a stable gel structure, and that this structure is stabilized with cross-links. Surprisingly the enzymatic treatment of flax seeds steeped in water in advance does not give any result at all. The experiments of digestion directed to the gel from outside were unsuccessful; nevertheless, this method proved to be the most suitable from the point of view of retaining the sprouting ability.
We have found, however, that if the flax seeds are soaked in an aqueous enzyme solution containing at least one pectinolytic, cellulolytic and optionally proteolytic enzyme, the mucilage can be separated from the surface of seeds, and the seeds keep their viability. These results were not predictable on the basis of the prior art at all. The sprouting experiments showed that the husk deprived of mucilage is not injured by the enzymatic treatment (it is important because the lignans are bound to the husk), in fact, it is so stable that the seeds can be effectively sterilized prior to sprouting with sodium hypochlorite solution of high concentration. The flax sprout obtained in such a way is free from mucilage, easy to digest, suitable for direct human consumption and can be employed in a lot of different fields.
Under the effect of enzymatic treatment according to this invention the mucilaginous material separates from the surface of seed on a gentle mechanical influence as a thick, mucilaginous solution. According to our working hypothesis the cross-links of complex gel structure and links between the mucilage and the husk, respectively, split on the influence of enzymatic treatment. This is supported by our observation that the viscosity of the separated mucilaginous material does not change even after intensive incubation (lasting several days). This allows for further processing of the mucilaginous material separated from the flaxseed.
The separation of mucilaginous material enabled us to work out a quick method for the purification and formulation of this material. We have found that at a low temperature (4° C.) the mucilaginous material precipitates from the aqueous solution already at a 40% (v/v) alcohol concentration. Through repeated alcohol washing and heat treatment the materials hindering the digestion (hydrocyanids and inhibitors) are removed.